Explosive and process for its manufacture



Patented Ag. 1, 1924.

UNITED: STATES PATENT OFFICE.

ll'o Drawing.

To all whom it may concern:

Be it known that I, ETIENNE HAnmi, residing at 1 Rue dHarcourt, Rouen,Seine-Inferieure, France, have invented certain new and usefulImprovements in Explosives and Processes for Their Manufacture, of whichthe following is a specification.

It is known that mixing mercury fulminate with fatty matters (oils,greases, paraflins, etc.,) renders the mercury fulminate less sensitiveto shock. Thus the detonating fuse employed by the Austrian armycomprises a core or mercury fulminate containing a high proportion ofparaffin.

When however as is usual the mercury fulminate is mixed with high(proportion of fatty matters, it is insensitize to such a degree that adetonator of pure fulminate is re uired to detonate it.

he fuhninate if it is to preserve its priming action can only be mixedwith a much smaller quantiy of fatty matters. Hitherto the proportion offatty matters mixed with the fulminate has been far lar er than issufiicient to render it insensitive owing to which insensitizedfulminate detonators have been used to the best advantage.

It has now been discovered that mercury fulminate is insensitized with afar smaller quantity of fatty matters than has hitherto been employed.Thus detonators charged in the ordinary manner with 1.2 grams oftrinitrotoluene or with picric acid or with tetryl may leave a verylarge quantity of unexploded material if detonated with 0.42 grammercury fulminate containing even 0.05% of its weight in oil. Butif thefulminate is not mixed with oil such quantity of fulminate is sufficientin all cases to cause complete detonation and this quantity of purefulminate has usually been employed in ractice. v

ccording to this invention an insensitized explosive still retaining itsfull priming power is produced by mixing lead azide with a much largerquantity of fatt matters (oils, greases, parafiins, etc.). T e quan-Application filed March 27, 1923. Serial No. 628,078.

tity of fatty matters which it is possible to incorporate with it wouldwith certainty render mercury fulminate insensitive: the quantity addedmay exceed 300 times that which suflices to insensitized mercuryfulminate. Thus lead azide may be mixed with up to 14% of its weight ofoils, greases or parafiins without its priming properties beingsubstantially modified and without it being necessary to employ aquantity of fatty azlde greater than the weight of pure normal fulminateto cause complete detonation. v

Detonators' charged with 1.2 grams of trinitrotoluene and primed with0.33 gram only of lead azide. and containing 12% par aflin never fail. l

The quantity of fatty azide to be added varies with. the proportion offatty matters incorporated. The table set out below by way ofillustration shows the quantities of fatty azide that experiment hasshown to be necessary practically to obtain the same effect as with thedetonators charged with 0.42 gram of pure fulminate:

0.33 gram. fatty azide containing 12% paraflin. I

0.65 gramv fatty azide containing 15% parafiin.

0.90 gram fatty azide containing 20% parafiin.

These compoun detonator whose lower charge is trimtrotoluene (T. N. T.).If tetryl (Eng lish and German detonators) which is much moresensitivebe employed in a compound charge, the quantities ofazide mayevidently be smaller. Thus detonators charged with tetryl require inpractice only a single charge of 0.15 gram azide admixed with 12% ofparaffin provided a top cap is employed.

' As will be seen, the quantity of azide varies with the quantity ofparaflin added and with the sensitiveness of the mixed charge. But withfulminate containing a like proportion of fatty matters there willalways bemisfires.

Parafiin for example may be admixed guantities of azide correspond to aa in a very simple manner either directly and with heat or y emplo ing aknown solvent of paraffin which is then evaporated.

Lead azide insensitized by means of parafiin allows fatted lead azide tobe obtained in the form of, small grains. The small grains are obtainedin any suitable manner,

or example by those which have been employed for granulating blackpowder. The advanta es obtained by the employment of such hig proportionof fatty matters and which form the object of the present inventionare:

1. An easier and less dangerous manipulation of the azide, dust iscompletely prevented by this coating.

2. The introduction of large quantities of solid parafiin or othergrease a lows explosive grains of the size desired easily to be obtainedby the use of sieves. If charging hoppers now in use are employed veryregular charges of the substance can be obtained.

3. The azide so coated is, if the quantity of fatty bodies besufficient, quite insensitive to the action of water.

Detonators whose layer of azide contains 10 to 12% of parafiin may befilled with water without in any way losing their explosive propertiesafter the water they contain has been poured off. The layer of fattyazide, being unwettable and impermeable to water, protects the layer ofcomressed trinitrotoluene or of tetryl below it at the bottom of thedetonator from the action of the water.

4. As water has no action on detonators.

thus constituted, vthe carbonic acid of the atmosphere has also noaction and one of the main defects in the use of lead azide is that itis attacked by carbonic acid which is often encountered in certainmines; to this cause several inexplicable accidents have been attributedwhich occurred when detonators containing lead azide were first used.Detonators whose lead azide contains a high proportion of paraiiin forexample, are thus very efiectively protected agalnst the action ofcarbonic acid and the humidity of the atmosphere.

5. Coating the azide with a fatty body "also has'for effect that thenitride has no action upon metals. It is known that so far as possibleazide should be charged in tubes other than the usual copper tubes;special precautions at least should be taken. It is known that thecarbonic acid of the atmosdangerous. Similar reactions need not beLesa-re? feared with the lead azide coated with a fatty bodyas abovedescribed.

6. The introduction of these hi h proportions of paraffin for example (Wich in no way diminishes the priming properities of the single azide)allows other bodies to be mixed with it such as-those employed in themanufacture of percussion caps for sporting or war cartridges. Themixture which is intimately bound by the paraffin, remains homogeneouswhatever may be the shock or manipulations to which it may be subjected.

7. Finally the high proportions of fatty matters which may also beintroduced into lead azide without practically weakening its primingproperties renders it more easily manipulable by diminishing itssensitiveness to shock. Azide containing 14% of paraflin is infinitelyless sensitive to shock than mercury fulminate.

Claims:

1. Process for obtaining a desensitized priming body which retains itsprimin properties which consists in mixing lea azide with a proportionof fatty matters greater than the minimum proportion which added tomercury fulminate would so inscnsitize the fulminate as so to reduce itspriming power that it would cause misfires.

2. Process for obtaining a desensitized priming body which retains itspriming properties, which consists in incorporatin with lead azide bymixture, a proportion 0% fatty matters greater than 0.05% and less than20%.

3. Process for obtaining a desensitized priming body which retains itspriming properties, which consists in incorporating with lead azide aproportion of about 14% of fatty matters.

4. Process for obtaining a desensitized priming body which retains itspriming properties and is suitable for being easily charged intodetonators, which consists in incorporating with lead azide a proportionof. solid fatty matters suflicient to granulate. the mass obtained.-

5. Process for obtaining a. desensitized priming body which retains itspriming properties and is suitable for being easily charged intodetonators, which consists in incorporating with lead azide a proportionof about 14% of paraifin and in granulating the mass obtained. r

6. A desensitized priming substance possessing a priming powersubstantially similar to that oflead azide, which contains a mixture oflead azide and fatty matters in the proportion of 0.05% to 20% withrespect to the lead azide.

7. A desensitizedpriming substance possessing primingpower practicallysimilar to that of lead azide, which contains a mixture of lead azideand fatty matters in a proportion of about 14% with respect to 9. A(letonator having as priming subthe lead azide. stance lead azicle withwhich is incorporated 8. A desensitized priming substance posone or morefatty matters in the proportion 10 sessing priming power practicallysimilar of 0.05-to 20%. i 5 to that of lead azide which contains amix-In testimon whereof I aflix my signature.

ture of lead azlde and about 12 to 14% of para-fiin. ETIENNE HARLE.

